Plants and other organisms interact in a myriad of ways in terrestrial ecosystems and the basis of communication among and within species is a source of intense interest, from molecular to global scales. While we think of DNA as the code that provides the genetic information of all organisms, recent discoveries on the functions of fragmented extracellular DNA (eDNA) outside the cell have opened a new arena for our understanding of biotic interactions. In this issue of New Phytologist, the Editors’ Choice is a perspective piece by Vereslogou and colleagues, which explores a provocative phenomenon observed in plant litter (Mazzeloni et al., 2015) on the role of self eDNA in inhibiting growth and seed germination of plants of the same species. The authors of the original research interpreted the observed reduction in growth to a toxic effect of the self eDNA –that is, that the self DNA (as opposed to eDNA from other species) acts to inhibit growth, which the organisms are able to recognize and distinguish from other non-self eDNA fragments.

Vereslogou and colleagues (and see Commentary by Duran-Flores & Heil, 2015) suggest another explanation, that is not mutually exclusive, which is that the self eDNA actually functions as a signalling molecule for other plants of the same species – that is, plants that release eDNA fragments generally do so as a function of stress – which means that these fragments could be seen as a new form of a damage-associated molecular pattern (DAMP). Rather than a toxic effect, these self eDNA fragments serve to identify a hostile environment for conspecific individuals – a way of communicating that the present environment may not be the most hospitable for germination and growth.

Whether self eDNA serves as a friendly warning or a toxic avenger has yet to be determined, and there is still much work that needs to be done to establish the generality of these patterns across organisms and ecosystems. What is most interesting for me is to see the intersection of disciplines bringing to light a new and interesting insight into the ways in which organisms interact and communicate in their natural environment.